U.S. patent application number 13/885922 was filed with the patent office on 2013-09-12 for process for extracting aluminum from aluminous ores.
The applicant listed for this patent is Serge Alex, Fabienne Biasotto, Richard Boudreault, Joel Fournier. Invention is credited to Serge Alex, Fabienne Biasotto, Richard Boudreault, Joel Fournier.
Application Number | 20130233130 13/885922 |
Document ID | / |
Family ID | 46083447 |
Filed Date | 2013-09-12 |
United States Patent
Application |
20130233130 |
Kind Code |
A1 |
Boudreault; Richard ; et
al. |
September 12, 2013 |
PROCESS FOR EXTRACTING ALUMINUM FROM ALUMINOUS ORES
Abstract
There is provided a method for extracting aluminum ions from
argillite. The process comprises leaching the argillite with an
acid such as HCl so as to obtain a composition comprising the
aluminum ions and iron ions; at least partially removing the iron
ions from the composition by substantially selectively
precipitating the iron ions by adding a base and at least partially
removing the precipitated iron ions so as to obtain an Al-rich
composition; and optionally purifying the Al-rich composition by
adding a base for substantially selectively precipitating the
aluminum ions, by means of a hollow fiber membrane, or by a
liquid-liquid extraction.
Inventors: |
Boudreault; Richard;
(St-Laurent, CA) ; Alex; Serge; (Quebec, CA)
; Biasotto; Fabienne; (Outremont, CA) ; Fournier;
Joel; (Carignan, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Boudreault; Richard
Alex; Serge
Biasotto; Fabienne
Fournier; Joel |
St-Laurent
Quebec
Outremont
Carignan |
|
CA
CA
CA
CA |
|
|
Family ID: |
46083447 |
Appl. No.: |
13/885922 |
Filed: |
November 18, 2011 |
PCT Filed: |
November 18, 2011 |
PCT NO: |
PCT/CA2011/001271 |
371 Date: |
May 16, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61415473 |
Nov 19, 2010 |
|
|
|
Current U.S.
Class: |
75/743 ; 423/112;
423/127 |
Current CPC
Class: |
Y02P 10/234 20151101;
C22B 21/0007 20130101; C22B 21/0015 20130101; C22B 3/22 20130101;
Y02P 10/20 20151101; C22B 3/44 20130101; C22B 3/10 20130101; C22B
3/0005 20130101 |
Class at
Publication: |
75/743 ; 423/112;
423/127 |
International
Class: |
C22B 21/00 20060101
C22B021/00 |
Claims
1. A process for extracting aluminum ions from argillite, said
process comprising: leaching said argillite with HCl at a pressure
of about 150 KPa to about 850 KPa so as to obtain a composition
comprising said aluminum ions and iron ions; at least partially
removing said iron ions from said composition by substantially
selectively precipitating at least a portion of said iron ions at a
pH of about 3 to about 6 by reacting said composition with a base
and at least partially removing said precipitated iron ions so as
to obtain an Al-rich composition; and optionally purifying said
Al-rich composition by: substantially selectively precipitating
said aluminum ions; by means of a hollow fiber membrane; or by
means of a liquid-liquid extraction.
2. (canceled)
3. The process of claim 1, wherein said argillite is leached with
HCl at a temperature of at least 90.degree. C.
4. The process of claim 1, wherein said argillite is leached with
HCl at a temperature of about 100.degree. C. to about 110.degree.
C.
5. The process of claim 1, wherein said HCl has a concentration of
about 6 M or about 12 M.
6. (canceled)
7. The process of claim 1, wherein said process comprises: leaching
said argillite with HCl at a pressure of about 150 KPa to about 850
KPa so as to obtain a leachate comprising said aluminum ions and
said iron ions, and a solid residue; separating said leachate from
said solid residue; at least partially removing said iron ions from
said leachate by substantially selectively precipitating said at
least a portion of said iron ions by reacting said base with said
leachate and removing a so-formed precipitate, so as to obtain said
Al-rich composition; and purifying said Al-rich composition by
substantially selectively precipitating said aluminum ions by
reacting said composition with an acid or a base, and by recovering
said precipitated aluminum ions.
8. The process of claim 1, wherein said process comprises: leaching
said argillite with HCl at a pressure of about 150 KPa to about 850
KPa so as to obtain a leachate comprising said aluminum ions and
said iron ions, and a solid residue; separating said leachate from
said solid residue; at least partially removing said iron ions from
said leachate by substantially selectively precipitating said at
least a portion of said iron ions by reacting said base with said
leachate and removing a so-formed precipitate, so as to obtain said
Al-rich composition; and purifying said Al-rich composition by
means of a hollow fiber membrane, or by a liquid-liquid
extraction.
9. The process of claim 1, wherein said process comprises: leaching
said argillite with HCl at a pressure of about 150 KPa to about 850
KPa so as to obtain a leachate comprising said aluminum ions and
said iron ions, and a solid residue; separating said leachate from
said solid residue; at least partially removing said iron ions from
said leachate by substantially selectively precipitating said at
least a portion of said iron ions by reacting said base with said
leachate and removing a so-formed precipitate, so as to obtain said
Al-rich composition; and purifying said Al-rich composition by
substantially selectively precipitating said aluminum ions and
recovering said precipitated aluminum ions.
10. The process of claim 1, wherein said Al-rich composition is
purified by complexing said aluminum ions with an extracting agent
so as to obtain a complex, separating said complex from said
composition and precipitating said aluminum ions.
11. The process of claim 10, wherein said extracting agent is
bis(2,4,4-trimethylpentyl)phosphinic acid.
12-19. (canceled)
20. The process of claim 1, wherein said iron is at least partially
removed from said argillite by substantially selectively
precipitating said at least a portion of said iron ions at a pH of
about 3 to about 5 by adding said base.
21. The process of claim 1, wherein said iron is at least partially
removed from said argillite by substantially selectively
precipitating said at least a portion of said iron ions at a pH of
about 3 to about 4 by adding said base.
22-23. (canceled)
24. The process of claim 1, wherein said iron is at least partially
removed from said argillite by substantially selectively
precipitating said at least a portion of said iron ions at a pH of
about 4 to about 5 by adding said base.
25. (canceled)
26. The process of claim 1, wherein said Al-rich composition is
purified by adding a base for substantially selectively
precipitating said aluminum ions at a pH of about 5 to about 6 and
recovering said precipitated aluminum ions.
27-28. (canceled)
29. A process for extracting aluminum ions from an aluminosilicate
ore, said process comprising: leaching said aluminosilicate ore
with an acid so as to obtain a composition comprising said aluminum
ions and iron ions; at least partially removing said iron ions from
said composition by substantially selectively precipitating at
least a portion said iron ions at a pH of about 3 to about 5 by
reacting said composition with a base and at least partially
removing said precipitated iron ions so as to obtain an Al-rich
composition; and purifying said Al-rich composition by:
substantially selectively precipitating said aluminum ions at a pH
of about 5 to about 6 by reacting said Al-rich composition with a
base and recovering said precipitated aluminum ions; or by means of
a hollow fiber membrane.
30. A process for producing alumina comprising obtaining aluminum
ions by means of a process as defined in claim 1; and converting
said aluminum ions into alumina.
31. (canceled)
32. A process for producing aluminum comprising obtaining alumina
by means of a process as defined in claim 30; and converting said
alumina into aluminum.
33. The process of claim 1, wherein said leaching with HCl is
carried out at a pressure of about 150 KPa to about 750 KPa.
34. The process of claim 10, wherein said leaching with HCl is
carried out at a pressure of about 200 KPa to about 600 KPa.
35. The process of claim 20, wherein said leaching with HCl is
carried out at a pressure of about 250 KPa to about 500 KPa.
36. A process for extracting aluminum ions from an aluminosilicate
ore, said process comprising: leaching said aluminosilicate ore
with an acid so as to obtain a composition comprising said aluminum
ions and iron ions; at least partially removing said iron ions from
said composition by precipitating at least a portion said iron ions
so as to obtain an Al-rich composition; and purifying said Al-rich
composition by: substantially selectively precipitating said
aluminum ions at a pH of about 5 to about 6 by reacting said
Al-rich composition with a base and recovering said precipitated
aluminum ions; or by means of a hollow fiber membrane.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to improvements in the field
of chemistry applied to extraction of aluminum from aluminous ores.
For example, such processes are useful for extracting aluminum from
aluminous ores comprising various types of metals such as Fe, K,
Mg, Na, Ca, Mn, Ba, Zn, Li, Sr, V, Ni, Cr, Pb, Cu, Co, Sb, As, B,
Sn, Be, Mo, or mixtures thereof.
BACKGROUND OF THE DISCLOSURE
[0002] More than 96% of the alumina which is produced worldwide is
obtained from bauxite, which is a mineral that is particularly rich
in alumina (40-60%) and whose main suppliers are from Jamaica,
Australia, Brazil, Africa and Russia. In certain areas of the world
there are large quantities of aluminous ores, which are
aluminosilicates (for example argillite, nepheline, etc.) that are
relatively rich in alumina (20-28%). However such areas have
received little attention up to now because the production costs
for extracting aluminum from such ores remained too high. In these
aluminous materials, and contrary to bauxite, aluminum oxide is
associated with silicated or sulfated phases. Thus, the Bayer
process cannot be used, which means that alternative treatments for
the production of alumina must be used or developed. Various
processes have been proposed so far in order to extract aluminum
from such aluminous ores comprising aluminosilicates but there is
still room for improvement or for alternative routes.
SUMMARY OF THE DISCLOSURE
[0003] According to one aspect, there is provided a process for
extracting aluminum ions from argillite, the process comprising:
[0004] leaching the argilite with HCl; [0005] at least partially
removing iron from the argillite by substantially selectively
precipitating at least a portion of the iron ions by reacting the
iron ions with a base so as to obtain an Al-rich composition or by
substantially complexing the iron ions with an extracting agent;
and [0006] optionally purifying said Al-rich composition by: [0007]
substantially selectively precipitating said aluminum ions; [0008]
by means of a hollow fiber membrane; or [0009] by means of a
liquid-liquid extraction.
[0010] According to another aspect, there is provided a process for
extracting aluminum ions from argillite, the process comprising:
[0011] leaching the argillite with HCl so as to obtain a
composition comprising the aluminum ions and iron ions; [0012] at
least partially removing the iron ions from the composition by
substantially selectively precipitating at least a portion of the
iron ions by reacting the composition with a base and at least
partially removing the precipitated iron ions so as to obtain an
Al-rich composition; and [0013] optionally purifying said Al-rich
composition by: [0014] substantially selectively precipitating said
aluminum ions; [0015] by means of a hollow fiber membrane; or
[0016] by means of a liquid-liquid extraction.
[0017] According to another aspect, there is provided a process for
extracting aluminum ions from an aluminous ore, the process
comprising: [0018] leaching the aluminous ore with HCl; [0019] at
least partially removing iron from the aluminous ore by
substantially selectively precipitating at least a portion of the
iron ions by reacting the iron ions with a base so as to obtain an
Al-rich composition or by substantially complexing the iron ions
with an extracting agent; and [0020] optionally purifying said
Al-rich composition by: [0021] substantially selectively
precipitating said aluminum ions; [0022] by means of a hollow fiber
membrane; or [0023] by means of a liquid-liquid extraction.
[0024] According to another aspect, there is provided a process for
extracting aluminum ions from an aluminous ore, the process
comprising: [0025] leaching the aluminous ore with an acid so as to
obtain a composition comprising the aluminum ions and iron ions;
[0026] at least partially removing the iron ions from the
composition by substantially selectively precipitating at least a
portion of the iron ions by reacting the composition with a base
and at least partially removing the precipitated iron ions so as to
obtain an Al-rich composition; and optionally purifying said
Al-rich composition by: [0027] substantially selectively
precipitating said aluminum ions; [0028] by means of a hollow fiber
membrane; or [0029] by means of a liquid-liquid extraction.
[0030] According another aspect, there is provided a process for
extracting aluminum ions from a mixture comprising iron ions and
the aluminum ions. The process comprises recovering the aluminum
ions from a composition comprising the aluminum ions, the iron
ions, an organic solvent and an extracting agent adapted to form an
organometallic complex substantially selectively with the iron ions
or with the aluminum ions which is soluble in the organic
solvent.
[0031] It was found that the processes of the present disclosure
are effective for extracting aluminum from various aluminous ores.
More particularly, it was found that such processes were efficient
for extracting aluminum from ores having a considerable amount of
iron such as argillite. Such processes were thus found to be an
interesting alternative to the Bayer process. In fact, the Bayer
process was found not to be efficient for extracting aluminum from
certain ores such as ores having a high iron content (for example
argillite).
BRIEF DESCRIPTION OF DRAWINGS
[0032] In the following drawings, which represent by way of example
only, various embodiments of the disclosure:
[0033] FIG. 1 shows a bloc diagram of a process according to one
embodiment of a process for extracting aluminum from an aluminous
ore.
DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS
[0034] The acid used for leaching the aluminous ore can be HCl,
H.sub.2SO.sub.4, HNO.sub.3 or mixtures thereof. More than one acid
can be used as a mixture or separately. Solutions made with these
acids can be used at various concentration. For example,
concentrated solutions can be used. For example, 6 M or 12 M HCl
can be used. For example, up to 100% wt H.sub.2SO.sub.4 can be
used.
[0035] The processes of the present disclosure can be effective for
treating various aluminous ores or aluminum-bearing ores. For
example, clays, argillite, mudstone, beryl, cryolite, garnet,
spinel, bauxite, or mixtures thereof can be used as starting
material.
[0036] The leaching can be carried out under pressure into an
autoclave. For example, it can be carried out at a pressure of
about 5 KPa to about 850 KPa, about 50 KPa to about 800 KPa, about
100 KPa to about 750 KPa, about 150 KPa to about 700 KPa, about 200
KPa to about 600 KPa, or about 250 KPa to about 500 KPa. The
leaching can be carried out at a temperature of at least 80.degree.
C., at least 90.degree. C., or about 100.degree. C. to about
110.degree. C. In certain cases, it can be done at higher
temperatures.
[0037] The leaching can also be carried out under pressure. For
example, the pressure can be about 100 to about 300 or about 150 to
about 200 psig. The leaching can be carried out for about 30
minutes to about 5 hours. It can be carried out at a temperature of
about 60.degree. C. to about 200.degree. C.
[0038] According to one embodiment, the process can comprise:
[0039] leaching the argillite with HCl so as to obtain a leachate
comprising the aluminum ions and the iron ions, and a solid
residue; [0040] separating the leachate from the solid residue;
[0041] at least partially removing the iron ions from the leachate
by substantially selectively precipitating at least a portion of
the iron ions by reacting the base with the leachate and removing a
so-formed precipitate, so as to obtain an Al-rich aqueous
composition; and [0042] purifying the Al-rich aqueous composition
by substantially selectively precipitating the aluminum ions by
reacting the composition with an acid or base, and by recovering
the precipitated aluminum ions.
[0043] According to another embodiment, the process can comprise:
[0044] leaching the argillite with HCl so as to obtain a leachate
comprising the aluminum ions and the iron ions, and a solid
residue; [0045] separating the leachate from the solid residue;
[0046] at least partially removing the iron ions from the leachate
by substantially selectively precipitating at least a portion of
the iron ions by reacting the base with the leachate and removing a
so-formed precipitate, so as to obtain the Al-rich aqueous
composition; and [0047] purifying the Al-rich aqueous composition
by means of a hollow fiber membrane, or by a liquid-liquid
extraction.
[0048] According to another embodiment the process can comprise:
[0049] leaching the argillite with HCl so as to obtain a leachate
comprising the aluminum ions and the iron ions, and a solid
residue; [0050] separating the leachate from the solid residue;
[0051] at least partially removing the iron ions from the leachate
by substantially selectively precipitating at least a portion of
the iron ions by reacting the base with the leachate and removing a
so-formed precipitate, so as to obtain the Al-rich aqueous
composition; and [0052] purifying the Al-rich aqueous composition
by substantially selectively precipitating the aluminum ions and
recovering the precipitated aluminum ions.
[0053] For example, the Al-rich aqueous composition can be purified
by complexing the aluminum ions with an extracting agent so as to
obtain a complex, separating the complex form the composition and
precipitating the aluminum ions. For example, the extracting agent
can be bis(2,4,4-trimethylpentyl)phosphinic acid.
[0054] For example, the Al-rich aqueous composition can be purified
by complexing impurities contained in Al-rich aqueous composition
with an extracting agent, at least partially removing the complexed
impurities from the composition and precipitating the aluminum
ions. For example, the extracting agent can be chosen from
di-2-ethylhexyl phosphoric acid (HDEHP),
bis(2,4,4-trimethylpentyl)phosphinic acid and 2-ethylhexyl
phosphonic acid mono-2-ethylhexyl ester.
[0055] The base that can be used for substantially selectively
precipitating the iron ions can be KOH, NaOH, or a mixture
thereof.
[0056] The base that can be used for substantially selectively
precipitating the aluminum ions can be KOH, NaOH, or a mixture
thereof.
[0057] For example, in an acidic medium, the precipitation of iron
ions can be carried out at a pH of about 3 to about 6, about 3.0 to
about 5.5, about 3 to about 5, about 3 to about 4, about 3.0 to
about 3.5, about 3.5 to about 4.0, about 4.0 to about 5.0, about
4.0 to about 4.5, or about 4.5 to about 5.0.
[0058] For example, the Al-rich composition can be purified by
reacting the Al-rich composition with a base for substantially
selectively precipitating the aluminum ions at a pH of about 5 to
about 6, about 5.0 to about 5.5, or about 5.5 to about 6.0.
[0059] According to another aspect, there is provided a process for
producing alumina comprising: [0060] obtaining aluminum ions by
means of a process as defined in the present disclosure; and [0061]
converting the aluminum ions into alumina.
[0062] For example, the aluminum ions can be converted into alumina
by heating Al(OH).sub.3 at a temperature of about 800.degree. C. to
about 1200.degree. C.
[0063] According to another aspect, there is provided a process for
producing alumina comprising: [0064] converting the alumina into
aluminum.
[0065] According to another aspect, there is provided a process for
producing aluminum comprising: [0066] obtaining alumina by means of
a process as defined in the present disclosure; and [0067]
converting the alumina into aluminum.
[0068] According to another aspect, there is provided a process for
extracting aluminum from an aluminous ore, the process comprising:
[0069] leaching the aluminous ore with an acid so as to obtain a
leachate and a solid residue; [0070] removing at least a portion of
iron ions contained in the leachate by: [0071] (i) substantially
selectively precipitating the at least portion of the iron ions in
basic conditions in which the pH is of at least 10, so as to obtain
an aluminum enriched composition; or [0072] (ii) substantially
selectively complexing the at least portion of the iron ions with
an extracting agent adapted to form an organometallic complex
substantially selectively with the iron ions so as to obtain an
aluminum enriched composition.
[0073] In the processes of the present disclosure, the acid can be
HCl. The aluminuous ore can be leached with HCl at a temperature of
at least 80.degree. C., at least 90.degree. C., or about
100.degree. C. to about 110.degree. C. HCl can have a concentration
of about 6 M. The alunimuous ore/acid ratio can be about 1/10 in
weight by volume.
[0074] For example, the removal of the at least portion of iron
ions can be carried out by precipitating the iron ions from a basic
aqueous composition. The composition can comprise comprising NaOH
or KOH.
[0075] For example, the removal of the at least portion of iron
ions can be carried out by reacting the leachate with a base in
order to obtain a pH of at least 10 and precipitating the iron
ions.
[0076] For example, the precipitated iron ions can be separated
from the rest of the leachate by carrying out a filtration, a
decantation, a centrifugation, or mixtures thereof.
[0077] The processes can further comprise rinsing the obtained
precipitated iron ions with a basic solution. The basic solution
can have a concentration of about 0.01 M to about 0.02 M. The pH
can be at least 11, at least 12, about 10.8 to about 11.2, or about
11.5 to about 12.5. The process can further comprise purifying the
precipitated iron ions by means of a hollow fiber membrane.
[0078] The removal of the at least portion of iron ions can be
carried out by reacting the leachate, under acidic conditions, with
the extracting agent and an organic solvent in order to obtain a
composition comprising an acidic aqueous phase comprising aluminum
ions and an organic phase comprising iron ions complexed with the
extracting agent. The aluminum enriched composition can be obtained
by separating the aqueous phase from the organic phase. The aqueous
phase can have a pH of about 1 to about 2.5, or about 2. The
extracting agent can be chosen from di-2-ethylhexyl phosphoric acid
(HDEHP), bis(2,4,4-trimethylpentyl)phosphinic acid and 2-ethylhexyl
phosphonic acid mono-2-ethylhexyl ester). The extracting agent can
have a concentration of about 0.5 M to about 1.5 M in the organic
phase or about 1 M in the organic phase.
[0079] For example, the organic solvent can be chosen from
C.sub.5-C.sub.12 alkanes and mixtures thereof. The organic solvent
can be heptane. The composition can have a volumic ratio organic
phase:aqueous phase of about 1:1. The organic phase and the aqueous
phase can be separated by means of a filtration membrane. The
membrane can be a hollow fiber membrane. The membrane can comprise
polypropylene, polyvinylidene difluoride, or a mixture thereof.
[0080] After passing the composition through the membrane, the
aqueous phase can separated from the organic phase. The aluminum
ions can be recovered in the aqueous phase and the aqueous phase is
treated with a base (such as NaOH or KOH). The aqueous phase can be
treated with the base so as to obtain a pH of at least about 4. The
process can further comprise a separation by filtration to obtain
Al(OH).sub.3, which can be eventually washed.
[0081] For example, the aluminous ore can be crushed and roasted
before being leached.
[0082] For example, before removal of the iron ions, the leachate
is treated with a base.
[0083] For example, before removal of the iron ions, the leachate
can be distilled so as to reduce its volume.
[0084] For example, the process can further comprise at least
partially recovering the aluminum ions present in the aluminum
enriched composition.
[0085] For example, the aluminum enriched composition can be
treated with an extracting agent adapted to form an organometallic
complex substantially selectively with the aluminum ions in the
presence of an organic solvent and an acid solution in order to
form a composition comprising an acidic aqueous phase comprising
impurities and an organic phase comprising aluminum ions complexed
with the extracting agent. The aluminum ions can be recovered by
separating the aqueous phase from the organic phase. For example,
the aqueous phase can have a pH of about 2.5 to about 3.5. The
extracting agent can be a phosphinic acid or a derivative thereof.
The extracting agent can be bis(2,4,4-trimethylpentyl)phosphinic
acid. The extracting agent can have a concentration of about 10% to
about 25% v/v or about 20% v/v with respect to the organic solvent.
The organic solvent can be chosen from C.sub.5-C.sub.12 alkanes and
mixtures thereof. The organic solvent can be heptane. The
composition can have a volumic ratio aqueous phase:organic phase of
about 1:1 to about 1:3. The organic phase and the aqueous phase can
be separated by means of a membrane (for example a hollow fiber
membrane). The membrane can comprise polypropylene, polyvinylidene
difluoride, or a mixture thereof. The composition can be at a
temperature of about 30.degree. C. to about 50.degree. C., or about
35.degree. C. to about 45.degree. C. After passing the composition
through the membrane, the aqueous phase can be separated from the
organic phase. The complexed aluminum ions can be recovered in the
organic phase. The organic phase can then be treated with HCl so as
to obtain an aqueous composition comprising the aluminum ions. The
aluminum ions can be converted into Al(OH).sub.3 by contacting it
with a base. Al(OH).sub.3 can then be converted into
Al.sub.2O.sub.3. Such a conversion of Al(OH).sub.3 into
Al.sub.2O.sub.3 can be carried out at a temperature of about
800.degree. C. to about 1200.degree. C.
[0086] According to one embodiment, the composition can comprise an
acidic aqueous phase comprising aluminum ions and an organic phase
comprising iron ions complexed with the extracting agent and
wherein the aluminum ions are recovered by separating the aqueous
phase from the organic phase. The aqueous phase can have a pH of
about 1 to about 2.5 or of about 2. The extracting agent can be
chosen from phosphoric acids and derivatives thereof, and
phosphinic acids and derivatives thereof. For example, the
extracting agent can be chosen from di-2-ethylhexyl phosphoric acid
(HDEHP), bis(2,4,4-trimethylpentyl)phosphinic acid and 2-ethylhexyl
phosphonic acid mono-2-ethylhexyl ester. The extracting agent can
have a concentration of about 0.5 M to about 1.5 M in the organic
phase or of about 1 M in the organic phase. The composition can
have a volumic ratio organic phase:aqueous phase of about 1:1.
After extraction (passing the composition through the membrane),
the aqueous phase can be separated from the organic phase, and the
aluminum ions can recovered in the aqueous phase and the aqueous
phase can be treated with a base (for example NaOH, KOH, or a
mixture thereof). The aqueous phase can be treated with the base so
as to obtain a pH of at least about 4. The process can further
comprise treating the organic phase with HCl and isolating the iron
ions in the form of Fe.sup.3+.
[0087] According to another embodiment, the composition can
comprise an acidic aqueous phase comprising iron ions and an
organic phase comprising aluminum ions complexed with the
extracting agent, and wherein the aluminum ions are recovered by
separating the aqueous phase from the organic phase. The aqueous
phase can have a pH of about 2.5 to about 3.5. The extracting agent
can be a phosphinic acid or a derivative thereof. For example, the
extracting agent can be bis(2,4,4-trimethylpentyl)phosphinic acid.
The extracting agent can have a concentration of about 10% to about
25% v/v with respect to the organic solvent or of about 20% v/v
with respect to the organic solvent. The composition can have a
volumic ratio aqueous phase:organic phase of about 1:1 to about
1:3. During the process, the composition can be at a temperature of
about 30.degree. C. to about 50.degree. C. or at a temperature of
about 35.degree. C. to about 45.degree. C. After extraction through
the membrane, the aqueous phase can be separated from the organic
phase. The complexed aluminum ions can be recovered in the organic
phase. The organic phase can then be treated with HCl so as to
obtain an aqueous composition comprising the aluminum ions.
[0088] For example, the organic solvent can be chosen from
hydrocarbons. For example, the organic solvent can be chosen from
C.sub.5-C.sub.12 alkanes and mixtures thereof. The organic solvent
can also be hexane or heptane. The organic phase and the aqueous
phase can be separated by means of a filtration membrane, for
example a hollow fiber membrane. Such membrane can comprise
polypropylene, polyvinylidene difluoride, or a mixture thereof. The
aqueous phase can be treated with the base so as to obtain a pH of
at least about 4. The process can also further comprise a
separation by filtration so as to obtain Al(OH).sub.3. The process
can also comprise washing the Al(OH).sub.3. The process can also
comprise converting Al(OH).sub.3 into Al.sub.2O.sub.3. Conversion
of Al(OH).sub.3 into Al.sub.2O.sub.3 can be carried out at a
temperature of about 800.degree. C. to about 1200.degree. C.
[0089] According to another aspect there is provided a composition
comprising aluminum ions, iron ions, an organic solvent and an
extracting agent adapted to form an organometallic complex
substantially selectively with the iron ions or with the aluminum
ions which is soluble in the organic solvent.
[0090] According to another aspect, there is provided a composition
comprising an acidic aqueous phase comprising aluminum ions and an
organic phase comprising iron ions complexed with an extracting
agent.
[0091] According to another aspect, there is provided a composition
comprising an acidic aqueous phase comprising iron ions and an
organic phase comprising aluminum ions complexed with an extracting
agent.
[0092] According to another aspect, there is provided a process for
at least partially separating aluminum ions from iron ions
comprised in a composition, the process comprising substantially
selectively precipitating at least a portion of the iron ions in
basic conditions in which the pH is of at least 10. The iron ions
can be precipitated from a basic aqueous composition comprising
NaOH or KOH. For example, the base can be reacted with the
composition so as to obtain a mixture in which the pH is of at
least 10, and then, the at least portion of precipitated iron ions
can be separated from the rest of the mixture. For example, the
precipitated iron ions can be separated from the rest of the
mixture by carrying out a filtration, a decantation, a
centrifugation, or combinations thereof. The process can further
comprise rinsing the obtained precipitated iron ions with a basic
solution. The basic solution can have a concentration of about 0.01
M to about 0.02 M. The pH can be at least 11, at least 12, about
10.8 to about 11.2, or about 11.5 to about 12.5. The process can
further comprise purifying the precipitated iron ions by means of a
hollow fiber membrane.
[0093] The various parameters, embodiments and examples previously
described concerning the processes can also be applied, when
possible, to these compositions.
[0094] Further features and advantages will become more readily
apparent from the following description of various embodiments as
illustrated by way of examples only in the appended drawings
wherein:
[0095] As it can be seen from FIG. 1, such a process can comprise
various steps, and each of these steps can eventually be
individually considered has being a process.
Preparation of Argillite Sample
[0096] Argillite can be finely crushed in order to help along
during the following steps. For example, micronization can shorten
the reaction time by few hours (about 2 to 3 hours). In order to
remove most of the iron, a leaching step at room temperature is
optionally carried out between the crushing step and the roasting
step (see option 1). This operation is, for ex ample, carried out
with hydrochloric acid HCl (12 M) and an argillite/acid ratio
(weight/volume) of 1:5 is used. Depending on experimental
conditions (sizes of the particles, time of treatment, agitation
system), about 65% to about 93% of the iron can then be removed.
However, this leaching step can also bring in a certain percentage
of the aluminum (0-5%). The last step of the preparation of
argillite comprises roasting the pretreated argillite. This can be
accomplished at a temperature greater than 550.degree. C. for a
period of about 1 to 2 hours. For example, a heat treatment makes
it possible to increase the quantity of extracted aluminum by about
30% to about 40% for the same period of time. In others words, the
quantity of extracted aluminum is doubled. When leaching at room
temperature is carried out, a phase separation before roasting can
be made in order to recover the acid and reduce heating costs.
Acid Leaching
[0097] Acid leaching comprises reacting the crushed and roasted
argillite with a hydrochloric acid solution at elevated temperature
during a given period of time. For example, the argillite/acid
ratio can be of about of 1:10 (weight/volume), the HCl
concentration can be of about 6 M, the temperature can be of about
100.degree. C. to about 110.degree. C., and the reaction time can
be of about 5 to about 7 hours. Under such conditions, more than
about 90% of the aluminum and about 100% of the iron can be
extracted in addition to impurities.
[0098] During the second half of such a treatment (for example the
last 2 or 3 hours), a portion of the acid can be recovered by
condensation. Once the extraction is terminated, the solid
(argillite impoverished in metals) can be separated from the liquid
by decantation or by filtration, after which it is washed. The
residual leachate and the washing water may be completely
evaporated. The corresponding residue can thereafter be washed many
times with water so as to decrease acidity and to lower the
quantities of sodium hydroxide (NaOH) that are required to adjust
the pH during iron removal. Final volume accounts for 10% to 20% of
initial volume. The acid recovered will can be re-utilized after
having adjusted its titer either by adding gaseous HCl, or by
adding concentrated HCl (12 M). After the reaction, the titer of
the acid can vary from about 4 M to about 6 M depending on
experimental conditions. With respect to the solid, it represents
about 65% to about 75% of the initial mass of argillite, it can be
valorized and be used again either as an ion exchange resin, or as
an adsorbent.
Removal of Iron
[0099] Removal of iron can be carried out by precipitation of the
iron ions in (i) basic medium or (ii) an acidic medium. For
example, in a basic medium, precipitation can be carried out at a
pH of at least 10 or at a pH of about 11.5 to about 12.5. For
example, in an acidic medium, the precipitation can be carried out
at a pH of about 3 to about 6, about 3 to about 5, about 3 to about
4, about 3.0 to about 3.5, about 3.5 to about 4.0, about 4.0 to
about 5.0, about 4.0 to about 4.5, or about 4.5 to about 5.0, by
adding the base. Such a step under basic or acidic conditions can
be made by adding NaOH or KOH for example at a concentration of
about 0.1 M to about 18 M. For examples, a concentration of 0.1 M,
1 M, 6 M or 10 M can be used. Then, all that is required is to
separate the solid portion from the liquid portion by filtration,
decantation or centrifugation and to rinse the solid by means of a
diluted base, such as a solution of NaOH (for example NaOH at a
concentration of 0.01 M to 0.02 M). Then, the solid is washed with
distilled water. The liquid portion comprises aluminum and
alkaline-earths A substantially complete removal of the iron and of
nearly all the impurities (other metals) can thus be achieved.
Optionally, it is possible to recover iron by using a refining step
by liquid-liquid extraction through a hollow fiber membrane (see
option 2).
[0100] Alternatively (see option 3), removal of iron can be carried
out by using an extracting agent and a hollow fiber membrane.
Various extracting agents that could substantially selectively
complex iron ions over aluminum ions (or aluminum ions over iron
ions) could be used in such a step depending an Al/Fe ratio. For
example, extraction can be carried out by using HDEHP
(diethylhexylphosphoric acid) as an extracting agent adapted to
complex iron ions. A concentration of about 1 M of HDEHP can be
used in an organic solvent, such as heptane or any hydrocarbon
solvent. Such an extraction can require relatively short contact
times (few minutes). For example, the pH of the order of 2 can be
used and aqueous phase/organic phase ratio can be of about 1:1. It
was observed that is possible to extract from 86% to 98% iron under
such conditions. It will be understood that in the present case,
iron is trapped in the organic phase. To recover iron in an aqueous
phase, a reverse extraction with hydrochloric acid (2 M or 6 M) and
organic phase/acidic phase ratio of about 1:0.5 can then be carried
out. In such a case, the resulting aqueous phase is rich in
Fe.sup.3+ ions.
Aluminum Recovery
[0101] The solution obtained from the previous step using either
the precipitation or the extraction technique is relatively clean
and mainly contains aluminum for example about 90% to 95% (without
the alkaline-earths in the case of precipitation). Recovery of the
latter can be carried out by liquid-liquid extraction for example
by using a same hollow fiber membrane and an extracting agent that
is adapted to complex at least substantially selectively aluminum
over other metals or residues.
[0102] For example, bis(2,4,4-trimethylpentyl)phosphinic acid (such
as the one sold under the name Cyanex.TM. 272) can be used as an
extracting agent specific to aluminum. For example, this extracting
agent can be used at a concentration of about 20% v/v in an organic
solvent such as heptane. The ratios between the aqueous phase and
the organic phase can be of about 1:1 to about 1:3. For example,
the extraction temperatures can be of about 40.degree. C. and the
pH can be maintained at about 2.5 to about 3.5. It was observed
that such a technique makes it possible to extract more than 70-90%
of the aluminum.
[0103] After the aluminum has been trapped in the organic phase, it
can be recovered in the form of a concentrate of Al.sup.3+ ions by
using a back extraction. For example, the reverse extraction can be
carried out at a temperature of about 40.degree. C. with
hydrochloric acid (for example at a concentration of 6 M). Under
this condition, more than 90% of aluminum can be recovered. Then,
Al.sup.3+ can be converted into aluminum hydroxide Al(OH).sub.3 by
addition of NaOH. Finally, Al(OH).sub.3 can be converted into
alumina (alumina Al.sub.2O.sub.3) by roasting Al(OH).sub.3 for
example at a temperature of about 800.degree. C. to 1200.degree.
C.
[0104] The following non-limiting examples further illustrate the
disclosure.
EXAMPLES
Example 1
Preparation of Argillite Sample
[0105] Crushing of mudstone: The resulting micronization average
employed for the tests ranges between 10 and 50 microns.
[0106] Roasting: Crushed mudstone was roasted at least during 1
hour at a temperature of 600.degree. C. Its average composition
was:
TABLE-US-00001 Al.sub.2O.sub.3 21.0% Fe.sub.2O.sub.3 8.0% K.sub.2O
1.5% Na.sub.2O 0.9% TiO.sub.2 0.9% CaO 0.08% ZnO 0.06% SiO.sub.2
51.0%
Acid Leaching
[0107] 500 g of argillite crushed and roasted were added to 5
liters of hydrochloric acid 6 M. The mixture was then heated at
100.degree. C.-110.degree. C. during 7 hours.
[0108] After reaction, the liquid part was separated from the solid
part by filtration. The solid was washed with distilled water which
was added to the liquid portion. This washing makes it possible to
recover part of the aluminum trapped in the solid. This solid had a
dry mass of 345 .+-.-5 g, which corresponds to a loss of about 30%
-32%.
[0109] The remaining liquid part, containing aluminum, iron and a
great part of the impurities initially present in mudstone, was
reduced by evaporation at a temperature of 100.degree. C. to 90% of
its initial volume. Residual volume was then 50 mL. The liquid
compositions before and after evaporation were:
TABLE-US-00002 Evaporated leaching Leaching solution solution
Composition (%) Composition (%) [concentration (mg/L)]
[concentration (mg/L)] Aluminum 47.63 47.86 [9 250] [59 500] Iron
31.54 31.07 [6 125] [38 625] Alkaline-earths 19.30 19.53 (Na, Mg,
K, Ca) [3 749] [24 277] Other metals 1.53 1.54 [297.3] [1 920]
[0110] All the ions species seem to remain soluble.
Removal of Iron
[0111] The residual volume was slightly diluted (+25%) and
concentrated hydroxide sodium (10 M) was added until a pH higher
than 11.5 was reached. The formed precipitate was separated from
the solution by standard filtration and was washed several times
with NaOH diluted and hot ultra-pure water. The precipitate
contained all the iron and the majority of the metal impurities.
The filtrate contained in addition to ions Al.sup.3+ mainly
alkaline-earths and some following impurities:
TABLE-US-00003 Major filtrate impurities (%) Iron 0.14 Sodium 94.13
Alkaline-earths 5.71 (Mg, K, Ca) Other metals 0.02
[0112] Na+ came from soda and was also the Al(OH).sub.4.sup.-
counter-ion.
[0113] Other tests have been made for precipitating iron ions under
acidic conditions and more particularly at a pH of about 4.5 to
about 5.0 with 0.1 M, 1 M and 6M (twice) of NaOH and it was
observed that such an embodiment was efficient. In fact, it was
found that around a pH of about 4.6 to about 4.8, almost all the
iron was precipitated.
Aluminum Recovery
[0114] The filtrate is adjusted at a pH of 2.5 to 3.5 by addition
of HCl 6 M. The resulting solution is extracted by means of the
complexing agent, Cyanex 272, at a concentration of 20%
volume/volume in an organic solvent with a volumetric ratio of 1:1.
The extraction is carried out at a temperature of 40.degree. C. in
a membrane contactor with hollow fibers. In less than about 30 to
60 min, more than 85% of aluminum is extracted. The pH adjustment
is performed by a regulation loop controling the NaOH (10 M)
addition. Complexed Al.sup.3+ in Cyanex are then recovered by
carrying out a back extraction with HCl (6 M) at 40.degree. C. and
an organic phase/acid phase volumetric ratio of 1:0.5. After the
back extraction, the composition of the recovered acid phase
is:
TABLE-US-00004 Composition (%) Aluminum 92.81 Iron 0
Alkaline-earths 7.14 (Na, Mg, K, Ca) Other metals 0.05
[0115] To increase the percentage of purity, the Al.sup.3+ ions are
precipitated in the form of Al(OH).sub.3 hydroxide, then washed
several times with ultra-pure water. The composition of the
hydroxide becomes:
TABLE-US-00005 Composition (%) Aluminum 99.09 Iron 0
Alkaline-earths 0.88 (Na, Mg, K, Ca) Other metals 0.03
[0116] Further purification can be performed by
recrystallization
[0117] While a description was made with particular reference to
the specific embodiments, it will be understood that numerous
modifications thereto will appear to those skilled in the art.
Accordingly, the above description and accompanying drawings should
be taken as specific examples and not in a limiting sense.
* * * * *